Modern gasolines are unleaded in order to be compatible with catalytic convertors, and fuel injection has to be used in modern spark ignition engines, in order to achieve the required stoichiometric fuel/air mixtures. A typical fuel-injected spark ignition engine has multipoint fuel injection, in which fuel from the injectors impinges directly onto inlet valves. An unleaded base gasoline in such an engine tends to give rise to inlet valve deposits. A relatively new class of spark ignition engines is the class described as direct injection spark ignition engines, also known as gasoline direct injection engines; problems in such direct injection engines can arise with unleaded gasoline by fouling of injector nozzles.
For trouble-free running, modern direct injection spark ignition engines require automotive fuels having a complex set of properties which can only be guaranteed when use is made of appropriate gasoline additives. Such fuels usually consist of a complex mixture of chemical compounds and are characterized by physical parameters. Fuel additives are used among other things in order to avoid formation of deposits in the intake system and the intake valves of engines (keep-clean effect); on the other hand, fuel additives may be used in order to remove deposits already formed at the valves and in the intake system (clean-up effect). Special additives have been developed to reduce or minimise inlet valve deposits and also injector nozzle fouling.
Aliphatic primary, secondary and tertiary monoamines with C1- to C20-alkyl residues, C3- to C20-cycloalkyl residues or cycloalkyl residues are known as dispersant additives in gasoline fuels, preferably in combination with Mannich-type dispersant additives, from WO 04/050806. The said monoamines can be used in gasoline fuels together with other dispersants additives, such as polyisobutenyl monoamines or polyisobutenyl polyamines based on polyisobutene with a number average molecular weight of from 600 to 5000, and with polyether carrier oils, such as tridecanol butoxylate or isotridecanol butoxylate. The use of the said monoamines results in a reduction of injector nozzle fouling in direct injection spark ignition engines.
WO 03/076554 relates to the use of primary hydrocarbyl amines wherein the hydrocarbyl moiety has a number average molecular weight in the range of from 140 to 255 for reducing injector nozzle fouling in direct injection spark ignition engines, either for “keep clean” or for “clean-up” purposes of such engines. In Fuel D of the examples of WO 03/076554, a gasoline fuel was prepared by “dosing into the base fuel 645 ppmw of a commercial additive package ex BASF A.G., containing polyisobutylene monoamine (PIBA), in which the polyisobutylene (PIB) chain has a number average molecular weight (Mn) of approximately 1000, a polyether carrier fluid and an antioxidant, with further inclusion of 50 ppmw dodecylamine”. Fuel D was subjected to a clean-up test determining the average injector diameter reduction after running a direct injection spark ignition engine with this Fuel.
WO 90/10051 relates to a gasoline fuel composition containing an intake valve deposit control additive formulation comprising long-chain primary amines exhibiting typically C6-C40 aliphatic radicals as substituents, e.g. dodecyl amine (lauryl amine), in combination with fuel dispersants selected from polyalkenylamines (such as polyisobutyl amine) and Mannich bases, and with fluidizer oils such as refined napthenic lubricating oil or a polyolefin like polypropylene or polybutylene.
WO 2009/074608 relates to a fuel additive composition and to a fuel composition comprising nitrogen-containing dispersants selected from polyisobutenyl monoamines and polyisobutenyl polyamines, synthetic or mineral carrier oils and primary, secondary or tertiary amines. Suitable tertiary amines may exhibit three C1- to C30-hydrocarbyl residues, the majority of the examples listed for such tertiary amines exhibit three identical C1- to C30-hydrocarbyl residues, furthermore, N-methyldicyclohexylamine and N-ethyl-dicyclohexylamine are mentioned. The said amines are recommended as an intake valve clean-up booster in gasoline-operated port fuel injection internal combustion engines.
GB-A 2 260 337 relates to an fuel additive composition for dehazing distillate fuels such as diesel fuels which contain water, said composition comprising an alkoxylated amine such as an ethoxylated fatty amine, e.g. an ethoxylated cocoalkylamine, an ethoxylated tallowalkylamine, an ethoxylated soyaalkylamine or an ethoxylated octadecylamine.
WO 92/14805 relates to a motor fuel composition comprising a liquid fuel in the gasoline boiling range and an amount, sufficient to provide intake system cleanliness especially with port fuel injectors and intake valves, of a mixture of certain amino phenols and certain alkoxylated amines. The alkoxylated amines may be selected from ethoxylated fatty amines, e.g. based on coconut oil, soybean oil or tallow oil, exhibiting oleyl or stearyl radicals.
WO 02/079353 relates to a gasoline additive concentrate composition, comprising a solvent, an alkoxylated fatty amine and a partial ester having at least one free hydroxyl group and formed by reacting a fatty carboxylic acid and a polyhydric alcohol. Examples of alkoxylated fatty amines include diethoxylated tallowamine, diethoxylated oleyl-amine and diethoxylated stearyl amine. A typical example of a partial ester having at least one free hydroxyl group and formed by reacting a fatty carboxylic acid and a polyhydric alcohol is glycerol monooleate. The said gasoline additive concentrate composition increases fuel economy, reduces fuel consumption, reduces combustion emissions and decreases engine wear in gasoline internal combustion engines.
WO 03/083020 relates to a method of operating a spark-ignited or compression-ignited internal combustion engine, comprising introducing a nitrogen-containing detergent composition selected from (A) reaction products of a hydrocarbyl-substituted acylating agent and an amine, (B) hydrocarbyl-substituted amines, (C) Mannich reaction products and (D) polyetheramines. Detergent composition (B) may include hydroxyl-substituted fatty amines such as diethoxylated tallowamine, diethoxylated oleylamine, diethoxylated stearylamine or diethoxylated amines from soybean oil fatty acids.
WO 2008/115939 relates to a fuel additive concentrate, comprising a detergent, an antioxidant and a friction modifier including alkoxylated fatty amines such as diethoxylated tallowamine, diethoxylated oleylamine, diethoxylated stearylamine or diethoxylated amines from soybean oil fatty acids. The said fuel additive concentrate is recommended for use in nonhydrocarbonaceous fuels.
The performance of the additives of the art to reduce or minimise inlet valve deposits and/or injector nozzle fouling in direct injection spark ignition engines and their interrelationship with gasoline fuels and further fuel additives in fuel compositions may still be unsatisfactory. Furthermore, minimizing friction in direct injection spark ignition engines may also be unsatisfactory. It is, therefore, an object of the present invention to provide an improved additive for reducing inlet valve deposits and/or injector nozzle fouling and for modifying friction, and to provide an improved fuel additive formulation which allow an efficient control of deposits formed in the engine, especially an improved injector nozzle fouling clean-up and keep-clean performance, and of friction performance.